


Lab Accidents

by Aeris_Blue



Category: Undertale
Genre: Fire child, continued misuse of science, lab accident, swapped
Language: English
Status: In-Progress
Published: 2018-09-19
Updated: 2018-12-07
Packaged: 2019-07-14 13:12:07
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 8,767
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16041152
Author URL: https://archiveofourown.org/users/Aeris_Blue/pseuds/Aeris_Blue
Summary: Stand alone chapters of lab mishaps.





	1. Swapped

**Summary for the Chapter:**

> Gaster and Grillby find their souls relocated and are left to deal with the consequences.

**Notes for the Chapter:**

> This one was written for the Grillstertember prompt: Swapped. This is one of my favorite cliches so I was excited to write something for it.

Gaster squinted his eyes open before he squeezed them shut again: everything was blurry, and far too bright. He rested his back against the wall surprised by how far away it felt as he tried to collect what had happened. He was in the lab, working on- a project. It was new. He hummed with thought, it was something to do with sustaining souls outside of the monster form. Increasing the longevity of them. Yes, yes, that was right.

He folded his arms, his sense of touch felt completely disoriented as if he was surrounded with a bubble of water that cushioned around his grip. He peeled his eyes open but he’d done something to his vision when the experiment- backfired, everything was laced with something resembling heat waves, blurry and terribly unfocused. He shut his eyes again, he hoped it wasn’t permanent.

What caused it to go wrong? He’d sanitized all traces of foreign magic from the room he was working in and sealed the door. Only those with passcodes to his office could get in but he’d informed his assistants he was not to be disturbed. Asgore normally announced his arrival in advance. Someone had broken the seal on the experiment while his soul was still exposed. He drummed his fingers against his jaw, his fingers never quite seemed to make contact though.

He furrowed his brows but didn’t feel any real pull of magic when he did so, something was definitely off. He forced his eye sockets open to see himself through his blurry waves of vision. He was unconscious on the floor in what looked to be a terribly uncomfortable position, so was he, dead? No, he’d be dust- unless he wouldn’t be. This was what humans called an out of body experience right?

He took a breath, oddly hot, and raised his hands up to his eyes. They were bright orange with laces of yellow as the color danced in and out of view, it was fascinating to watch, almost like fire- oh. Oh no. He ran his hand along the edge of the familiar black vest and broad shouldered form. It was all familiar but definitely not his. 

He scanned around the floor where he, Grillby, fell to find his glasses. He pressed the lenses up to his face and the rippling waves stabilized to a more familiar view. The right lense had broken during the fall but otherwise seemed fine. Maybe he could fix this before Grillby woke up.

He curled his legs under himself and steadied himself with his hand pressed firmly to the wall. It seemed a complete unnecessary amount of preparation as his body raised without any pinching in his knees or pulling against his pelvic bone as his femur straightened up. In fact as he stood to Grillby’s full height, he didn’t feel any pain or aches at all. He gave a shy little glance to his form to make sure Grillby hadn’t awoken before he bounced cautiously a few times. He felt a thin line of a smile sear across his face.

He straightened himself up to stand proper, he needed to fix this. 

Everything felt so soft, the way his feet pressed against the glossy black shoes, the way his arms gently swayed at his side, the touch of the table as he moved to observe his notebook. The incident had turned the book to a different page, he pinched the paper between his fingers only for it to burn in his touch. Grillby read all of the time, why was he burning pages? 

He reached for the beaker he had been working out of but couldn’t quite get the flames to solidify enough to grasp it. He puffed haughtily and a stream of smoke escaped from where his mouth would be. Well, where his mouth was, Grillby seemed to have something akin to one underneath all of the flames after all.

He took a cleansing breath and focused on solidifying the flames, he thought of his own boney grip as he wrapped his fingers along the thin glass. He felt his temperature rise a bit in his excitement, his flames rippled in response until he lost his concentration and the beaker dropped to the floor. He spat out a curse that crackled like fireworks in his throat as his WingDings font attempted to brawl with the Language of the Flames.

He wrapped his arms around his midsection and coughed vehemently, soot fell to the table as it found its way out of his mouth. He grimaced as he straightened back up, was that normal? He couldn’t recall Grillby ever coughing, perhaps it was an involuntary response from his soul due to the sensation being familiar but not necessary in this form. 

All of that noise and Grillby hadn’t even so much as stirred. If he couldn’t pick up a beaker for more than a few seconds it might be best to inform Grillby of their current situation. He knelt down by the pile of bones, a little more harshly than he had intended but he didn’t feel any recoil as his knees smacked against the tile. 

He couldn’t help the sense of wrongness he felt as he gently nudged at his own humerus with not his digits. There wasn’t even the slightest indication his presence was recognized. Grillby had always been a heavy sleeper, on the rare occasions he slept, so he tried again with a bit more of an effort. Still no response. 

He rolled the sleeve up enough to expose the radius and ulna then wrapped his fingers around the bone. Huh, he was cold, he was probably always but it was odd that he’d be able to feel it through the flames. Interesting. A check revealed his stats were stable and definitely Grillby’s, he wished he had a physical attack stat like that. He drew out Grillby’s soul, it was so small, he cupped his hands around it surprised that not only was it nearly transparent but it was physically cold to the touch.

Grillby’s soul needed warmth, it was outside of its’ core and incapable of sustaining itself. Gaster buckled down and reached out to his form, the flames began to lick the air as his temperature rose. The soul pulsed, with each beat he could see less and less of his colors through the tiny shape until finally it lost its’ chilling edge. Gaster returned the soul then sat beside his body surprised at the cold spots against his fiery skin.

It was similar to exerting a muscle he supposed, it only took a few seconds before they relaxed into their usual state. Huh, he’d used something aside from magic. He’d be proud of himself if he hadn’t potentially harmed his friend in the first place. His hands cupped his face and he was disturbed a bit by the lack of curvature. Grillby very expressive but it was always in colors, Gaster hadn’t really recognized the lack of features, not that he had that much himself.

Grillby finally stirred, or he thought he did, it was more a vehemoth shaking that caused his bones to rattle. “Why is it so cold?” Grillby gasped, his voice had an odd accent to it that he couldn’t quite place. Was that what Gaster would sound like in Common? 

If that was the case then his body was capable but it was his soul that stored his font. Perhaps then it was capable for Common to be written over his soul, but how would one go about doing that? He heard the flames popping in his excitement and he tried to calm himself. He didn’t need to start any fires.

“Why are you so bright?” Grillby mumbled his eye sockets half sealed. He rubbed at his eyes but pulled away from the scratching touch. He wrapped his arms around himself, his sockets opened fully when he realized how little of himself was present. 

‘So there’s been an accident,’ Gaster signed a bit frustrated as his fingers attempted to meld together, not quite as dexterous or precise as he was used to. 

Grillby traced Gaster up and down several times before he moved his hands over his own form. The notion seemed to sink in when he looked down to his hands, his eye lights burnt a bright orange, “what did you do Gaster?” His voice was hot, angry, but Gaster couldn’t stop smiling at the sound of common, seeing his terrible WingDings overwritten with something understandable. Huh, he observed himself, he really was glowing.

‘You walked in on a closed experiment,’ Gaster signed pointedly.

“Gaster,” Grillby bit.

‘O-K, long story short our souls swapped hosts,’ Gaster sighed, ‘I don’t know how long this will last but hey its’ not that bad. We’re both here we can figure this out. Our souls are naturally going to want to migrate into their proper form so push come to shove as long as we stick together they’ll switch back.’

Grillby pulled his knees up to his chest, he let out a slight grunt at the effort, “Gaster I am freezing,” he wrapped his hands around his humeruses as his bones began to rattle, “and what did you do to my hands?”

Gaster looked down at Grillby’s hands, interesting, his soul was so accustomed to the feel of holes in his palms that when given a form that was more magic than physical it adapted. Gaster was so used to the sight he hadn’t even noticed, ‘it will go away when we switch back, I’m fairly certain.’

Grillby groaned, “my soul is trying to find something to sit in- against- it keeps fluttering against my- your ribs.”

‘Interesting,’ Gaster hummed. He hadn’t really thought about the sensation in his chest, everything was sort of fluttering, wavy, but his soul wasn’t used to feeling so entrapped. He was grateful it hadn’t tried to settle into the core stone, it probably would have burnt up. What would have happened then?

The rattling was getting louder, ‘I’m gonna go get all of the spare clothes I have in my office, maybe some burners, just try not to turn my bones into charcoal.’ He rose to his feet but was surprised by the cold boney hand ensnaring his wrist.

“Don’t leave me,” the invincible soldier actually sounded weak, nearly pathetic. Gaster swallowed, an incredibly unpleasant heat rolled down his throat. He crouched back down, here he’d said they needed to stick together and he was about ready to run off on his own. “Is this why you cling to me? Cause you’re this cold?” his eye lights were round disks as they looked up to him, so his pout was effective.

‘For me it’s more like a type of high. I don’t normally feel but when I’m with you I feel a lot,’ he felt his temperature rise and saw blues and pinks roll around in his flames, that didn’t sound like he thought it did. 

Grillby didn’t seem to notice, “can we go together?”

‘Of course,’ Gaster signed. He stepped back just enough to allow Grillby enough space to rise to his feet, apparently it was more difficult of a task than he remembered. Grillby pressed his back against the wall and attempted to slide up it but fell back down on his tailbone with a visible whence. He reached his hand up and tried to pull himself up from the wall but his legs didn’t seem interested in unfolding themselves from under him.

“Your dang legs are too long Dings,” Grillby grumbled. Gaster smirked as he extended his hand down to the skeleton who reluctantly took it. Gaster pulled surprised by the weightlessness of Grillby who nearly flew into him. Grillby’s shoulders bounced, “don’t know your own strength do you?”

He shrugged, ‘I’m borrowing it from a friend.’ 

Grillby laced his boney arm around Gaster’s neck and pressed his ribs, more so his soul, as close as physically possible. They started down the halls towards his office, Grillby played it up as if he’d been injured in the lab whenever someone passed by giving quick precise ‘I’m fine’s and ‘nothing to worry about’s to those that seemed concerned. 

Gaster was rather impressed how easily Grillby fell into his mannerisms, all of his hand signs were near perfect replicas of his own gestures. Even the way he carried his sockets, eye lights forward, one socket just barely narrower than the other, it all seemed as if he was looking into a mirror. The longer it went on the more he felt he was being mocked.

Grillby dropped his head with a moan as he looked up at the steps to the office, ‘all the way up there?’ He signed around Gaster’s neck, Gaster nodded. He sighed, “you are really old you know that? This. I’m pretty sure this is what old feels like.” Gaster furrowed his brows, maybe his flames went a bit more red, he really couldn’t tell how his trying to emote was affecting his colors. 

‘I go up those stairs everyday with no problem,’ he glared. Grillby groaned again but wrapped his free hand around the railing. It took a few steps but he figured out the rhythm of it enough to where, near the top of the steps, he was supporting himself more than leaning on Gaster. 

“I think I’m getting this whole joint thing down,” Grillby grinned as he carefully picked up his feet in a quick, almost jig like, motion.

Gaster habitually placed his hand on the scanner before he remembered he needed to use the access code, ‘you have joints Grillby,’ he curled his knee forward to prove his point.

“Yours is different,” he leaned against the railway. “You have this tiny little trickle of magic that you manipulate through the center of your bones to create movement,” he specified.

Gaster failed the code for the second time, ‘and your entire form is wrapped in magic, that’s why you have such a quick response time.’ He drummed his fingers against the base of his face, it was hardly the same feeling as bones against his skull but it was habit.

Grillby placed his hand on the scanner, “the narrow pathway of magic is also probably why I’m so cold.” The keypad beeped as the door slid open. Grillby slipped in front of Gaster, he pushed his shoulders back and straightened his spine to full length, his sockets fell from their rounded shape into more of a square, ‘and this is my office,’ he signed with a perfectly straight face.

‘Okay how do you do that?’ Gaster laughed, he immediately regretted it as flames burnt at his throat and crackled in his mouth when his WingDings lodged themselves in his throat. He coughed soot into his hand that was quickly burned away.

Grillby rubbed Gaster’s back as the monster buckled over, “what was that about?”

‘WingDings and the language of the Flames don’t mix,’ he puffed out a rim of smoke as his breathing regained its’ regular composure.

Grillby batted the smoke away as his sockets began to water, “that can get in your eyes?” He scrubbed at his sockets as faint trails of smoke escaped his mouth, “it tastes terrible,” he wheezed. Gaster covered his laugh as he tried his best not to laugh or risk starting the whole fit over again.

He opened his desk drawer to retrieve his emergency clothes, whether he spilt something in the lab or had to convince Asgore he had at least been home to change, he occasionally needed spares. He pulled out all of it with little care, ‘go ahead and wear what you want.’

Grillby looked over the selection as if he was borrowing from a friend's closet. They were both particular about what they wore, after being in the same tunics for decades the ability to wear anything else was a privilege they didn’t take lightly. Gaster smirked, or did his best impression of one, if they were anywhere close to the same size they’d probably trade clothes from time to time.

Grillby pulled open the closet door to look in the mirror, his sockets twitched in confusion, it was odd not seeing yourself in your reflection. He started to tug the sweater over his head when Gaster pulled it back down, ‘what are you doing?’

“It makes the most sense to put this on top, or do you often run around with six shirts on?” Grillby folded his arms across his chest and looked down at Gaster. 

That was different, no one looked down on him but the Boss Monsters, ‘go ahead.’

Grillby tugged off the sweater exposing the skeleton’s ribs. Misshapen, ugly, white slates that hung heavy against the negative space around it. Gaster pulled at the collar on his throat and Grillby traced his fingers over the ribs, “I forgot, sorry.”

Gaster tossed him a purple button down, Grillby looked the shirt over, “would you,” he fiddled with the shirt, “put your hand right here?” He tapped on his chest right over his soul.

Gaster considered this before he gently placed his hand where he was instructed. Grillby let out a happy exhale, he wrapped his boney hands around Gaster’s, a wide content smile plastered across his face. “I don’t envy you one bit,” Grillby chuckled.

Gaster’s felt his flames tense at the phrase but they quickly returned to their perpetual motion. “Your flames are green, you okay?” Grillby’s pale orange eye lights looked down to him, the color must be an impression of his soul, like Gaster’s hands. He was about to pull his hand away to sign but looking into his sockets it felt a bit cruel. He tapped his spare hand to Grillby’s, but actually his, ribs.

Grillby seemed to understand, he squeezed Gaster’s hand tightly then turned his attention back to the shirt. His fingers deftly laced the buttons through the holes, “this I do like though,” he straightened his shirt up then grabbed for the next one. Six button downs and one sweater later he finally shut the cabinet.

Gaster undid the bowtie around his neck, ‘something of yours,’ he attempted to tie it around Grillby’s sweater’s neck but he couldn’t get his fingers to move the way he wanted. Grillby took the fabric in his hands and tied it quickly, “see? Mine are all clumsy,” he chuckled. 

‘Might have something to do with the fact my soul punched a hole through them,’ Gaster leaned back on his desk. Grillby shrugged and leaned against the desk his ribs as nestled against Gaster’s form as he could get. His eye lights twitched up to Gaster sheepishly several times before he wrapped his arms around his waist.

“Are you okay? You didn’t even flinch,” Grillby smiled into Gaster’s side.

He shrugged, ‘perhaps because it’s not my body? Or maybe I feel guilty for how pathetic you look?’

Grillby rolled his eyelights, “I’m not pathetic I’m just cold,” he huffed.

They fell into silence as they absorbed the oddness of standing so close to themselves. ‘Would you do me a favor?’ Gaster looked down to Grillby, ‘would you talk to me? Just anything, your day before you ruined my experiment, whatever customer gave you the hardest time last night. Just talk.’

He saw the look, the one that fought between assuring him his Font wasn’t a problem and his impulse to do as he was asked, even if it was on his skull and not the flickering of flames he knew it. Grillby sighed but he began: there wasn’t anything odd or unique about the things he was speaking of but Grillby thrived on the little things. Cleaning the bar or his house gave him a sense of fulfillment because they were his. Talking with other monsters lightened his soul, they didn’t know the things he’d done but they didn’t ask him about it either.

Snowdin was doing wonders for Grillby, even if there had been a lot of concern with him moving to such a hazardous-for-him location it seemed the biting cold was what he needed. He knew everyone in the sleepy town even the ones that didn’t come to his bar on a regular basis. So much of his day was consumed by his work and yet he still managed to make rounds.

Everything was infinitely more fascinating hearing it from this foreign voice. It was coming from his body but it was neither his nor Grillby’s. It lilted with Grillby’s inflections but would occasionally slip into an accent that seemed noticeably odd on Grillby’s tongue, or lack thereof. 

Gaster was nearly lulled to sleep as he listened but he pulled himself awake, ‘magic Grillby!’

Grillby pulled back a bit in surprise, “what about it?”

Gaster weaved himself away from Grillby, ‘fire magic!’ He could feel the heat across his face cutting into a jagged smile. 

He held his palm up to the ceiling, “Gaster I really don’t think we should-” he was cut off by a bone bullet forming in the air in front of him.

Gaster’s expression grew lost in the flames, well that was certainly disappointing. He turned the bullet over his hand, of course his soul, regardless of body, would choose the shape most familiar to it. He’d been enamoured with the idea of casting flames since Grillby first started using the magic, if he was ever going to be capable it would be now. He dispersed the bullet to a shower of embers. 

“Will you stop grinning like that?” Grillby shook his head. Gaster summoned another bullet and sent it sailing through the air until it struck into the far wall, it dispersed as embers. 

‘Summon a bullet,’ he had a crazed look in his eyes as his smile threatened to cut his face in half.

“Gaster, one: I don’t know how, two: this room is far too small for practicing potentially unstable magic, and three: no,” Grillby folded his arms. His magic was linked to his physicality more than his actual magic it was rare that he actually summoned anything, especially lately. Gaster signed please a few times while his flames whispered tints of yellow into his glowing body.

Grillby held his palm up to the ceiling, it took several seconds before a bone shaped fiery pillar appeared in his hand. ‘Interesting, interesting,’ Gaster signed giddily. ‘Can you summon more?’

“Gaster, we are waiting until our souls miss home enough to go back we are not performing experiments,” Grillby’s eyes flickered like flames as he glared down to Gaster. 

‘Just one more,’ Gaster smiled.

“No,” Grillby scoffed.

‘One more, please,’ Gaster tried.

“You know, I don’t have nearly as effective of a pout as you do,” Grillby chuckled as Gaster’s flames lit up with streams of pinks.

‘Just one more,’ Gaster’s expression turned far too mischievous as deep purple, almost black, flames danced across his features. 

“Fine,” Grillby held his palm up and Gaster laced his fingers around Grillby’s, “what are you doing?”

‘Coaching,’ Grillby could feel Gaster’s magic, not his, pulling into his form. It didn’t sting as much as it usually did, the cold edge of the deep loneliness was cut off by tinges of his own warm magic. He shut his eyes and let Gaster puppeteer his magic, a decision he immediately regretted as he felt a strong pull on his soul as something far larger than a bullet was summoned. 

“Dings!” Grillby scolded as he looked at the mighty skull staring him down. It was oddly feline in composition straight down to the bright orange slit eye lights sitting in it’s sockets. A mane of fire crackled behind it as the bullet began to sway restlessly from side to side. “What did you do!?”

The monster in question had fallen into another coughing fit after trying to laugh in his childish excitement. Grillby let him collect himself on his own as he kept his eyes trained on the skull in front of him. 

He wheezed a puff of smoke as he straightened up, ‘I put your soul under the same conditions as mine when I summon my blasters. Due to the presence of my magic it seems to appear mostly skeletal but I imagine its’ shape would be the same,’ he rolled his wrist, ‘but on fire.’

He wrapped his hand around his throat as he tried to stifle another laugh, ‘but this looks pretty wicked.’

Grillby rolled his eyes, he didn’t like being the ‘no fun’ one but this could be really dangerous, the bullet already seemed incredibly agitated to exist- but it was making the room warmer. He placed his hand above the saber like fangs that extended down past the jaw and moved his hands back toward the chasm like sockets. All of it was hot to the touch not just the flaming mane.

‘Forgive my selfishness,’ Gaster signed after he’d finished gawking at it, ‘I’d just always been curious what a blaster made by your hand would look like.’

“It’s rather pointless though, I can already focus a torrent of flames,” he patted it. “But it is kinda cool,” he admitted in defeat.

Gaster smiled pleasantly as he leaned against it, ‘I bet it’s warm like you.’

The thought hadn’t ever crossed Grillby’s mind, was this what he felt like? He tapped his teeth together, an incredibly gritty sting of sensation, before he laid across it. If this was what he felt like he wondered why Gaster always kept a distance, he certainly wouldn’t if the roles were reversed, like they were now. 

He looked over to the, not skeleton, who seemed to be enjoying this experience a lot more than he was. Gaster had always been enamored with his form, his strength, the way his soul sustained itself, he must be having a hayday processing all of the information he could wrap his mind around. Grillby hadn’t ever wondered what it was like to be a skeleton, abstract thinking wasn’t exactly in him, but he could see why his friend had pursued strength for so long.

He felt rather small, pathetic but he’d never admit that to the monster across from him. Being able to perform an attack with this much power, this much intent, must mean a lot more to him than he’d realized. He’d always known Eternals were the only monsters seen to be on par with Boss Monsters but he didn’t realize that other monsters just existed differently.

‘Do you need help dispersing it?’ Grillby gave a curious look to Gaster’s hands, ‘you look really tired.’

Grillby pulled away from the inebriating warmth of the bullet and felt a weight at the base of his sockets, a sluggishness in the trickle of magic to his lanky bones. How did Gaster work for so long if this was how his body responded to fatigue? He stood back and extended his magic the skull disappeared in a shower of white. Grillby rubbed at his sockets still repulsed by the bone on bone texture.

Gaster sat on the stool at the far side of the room, Grillby slouched, surprised at just how easy it was for each vertebrae to relax, as he crossed over to Gaster. “Yeah,” he conceded, “where’s your cot?”

In one single movement Gaster wrapped his arms around Grillby and pulled him into his lap. Grillby squirmed in an attempt to escape the grip, “Dings no!” he groaned. He froze mid squirm as he recognized the situation, “this is payback isn’t it?” 

‘You better believe it,’ Gaster signed around Grillby.

He relaxed into the monsters form, it was just the right amount of soft and firm. His bones seemed to be able to rest comfortably between muscle-like grooves he’d never seen as that deep. The flicker of flames and their tiny roar that could only be heard when you were this close weighed his eyes heavy. He rested the back of his skull against Gaster’s shoulder, his eye sockets grew heavier, his soul slowed its’ pull of magic, until he was finally pulled into sleep.

When his eyes finally opened again after an undetermined amount of time he looked down to the skeleton he was holding firmly in his arms. He nuzzled his face against the skeleton’s skulll, “hey,” his voice crackled oddly from whatever Gaster’s coughing fits had strained, “our souls are back.”

Gaster’s long nimble white fingers twitched wordlessly as a sound similar to a pulley system being operated underwater spoke up to him. He took that to be WingDings for ‘five more minutes’, he positioned himself to sit more comfortably in the chair, he’d give him ten.

**Notes for the Chapter:**

> These are going to be just for funzies style stories that I’ll write as I am inspired to.


	2. Timeline Flare

**Summary for the Chapter:**

> A smile child appears out of nowhere and neither Grillby nor WingDings know what to do.

**Notes for the Chapter:**

> Again these are just sort of stress relievers. Simple pieces I don’t stress over a bunch. They also aren’t all going to be Grillby and Gaster it just happened that way haha (the one that was going to be next was Gaster and the boys but I couldn’t get an ending on it)

‘Okay Dings, what are you messing with now?’ Grillby worried over the skeleton who had assembled some sort of an atrocity together that he couldn’t make heads or tails of.

‘This is very delicate work, I can’t look up to see your hands, just be patient!’ WingDings’s magic hand bullets signed. Grillby let out a groan when he plopped atop a nearby stone. Stones, stones, everywhere, there wasn’t anything to see down here. Well, that wasn’t true, past Home there were all sorts of oddities but he really didn’t want to force himself through that iceland just for a change in scenery.

If he was going to be stuck here supervising yet another mechanical mishap from the too-smart-for-his-own-good monster he should at least get comfortable.

He stripped his palderon’s off to unfasten his breastplate before he discarded the pieces entirely relieved to feel his flames fight there way into the air. His fleck like eyes scrunched while his hand rubbed against his face as he contemplated the move at hand. Hotlands was much more of an ideal location for him and being able to help start the settlements there was an honor he was happy to take but he couldn’t shake this terrible paranoia that without his presence this silly skeleton was going to blow himself up. 

No, he should trust his friend. But it was eating at him. He couldn’t place why the idea of being away from the monster was twisting his stomach into knots and dimming his flames. They’d been apart before so it wasn’t that. He rubbed the back of his neck, something was making his flames out of sorts.

A grinding sound much worse than a sword through a shield echoed around the cavern in a high pitched wail that was nothing short of deafening. Grillby screwed his hands over the side of his head, as if that would actually help, as he watched a white light dance in front of WingDings’s face. It cast sparks around the cavern until a bright red light devoured the surrounding area which left the air eerily still.

“Dings?” Grillby’s voice croaked.

A strange backlash of conflicting mechanical noises informed him his friend was still alive at least. It took several seconds for his vision to realign itself before WingDing’s frustrated expression as he laid flat on his back registered. Grillby couldn’t help but chuckle, “another set back huh?” WingDings’s eyelights rolled about in his head in an over the top display of his annoyance before he sat up.

‘I don’t understand what-’ his hands were wrapped in leather gloves that made it difficult to make since of his signing. He was about to rip them off in frustration before a quiet sob of sound bounced around the cavern. 

Grillby looked over to the mechanism that was smoldering in a red flame. It took him a moment to make out the arms cupped over the face, the knees curled into the chest, and the small bobbing head of a young flame. Several dots formed in his mind until he connected them to recognize the flame as a monster. A young eternal? But that can’t be the case that hardly counted as a disaster and this child was fully formed already.

WingDings observed Grillby’s line of attention the sighed. He bundled up the blanket he’d brought along just in case such a thing happened to smother out the lingering remains of his failure. Grillby put his hand up to stop him then crouched down to the small child.

His flames swayed from side to side as he contemplated what to do. The child was beside themselves sobbing uncontrollably into their hands completely unaware of the world around them. Grillby crackled a greeting, allowed his flames to sway pleasantly, and brightened his glow. Slowly, uncertainly, the child pulled their hands away from their eyes, two bright orange flecks that stood out against their purple face. The dancing red flames that twitched atop their head pulled close to their core before they ruptured away from him, “Daddy!”

Before Grillby could react to the accusation the child had thrown themselves at him with their arms wrapped tightly around his neck. “I was so scared! Everything went bright and then dark and cold,” he wailed into the fire monster’s collar bone.

WingDings and Grillby shared as close to matching expressions of bewilderment as they could muster. 

Grillby rested his hands against the child’s back before he gently nudged them away to stand at an observable distance. They were wearing a long sleeved shirt with a pouch on the front and a hood in the back, like a closed cape of some sort. It was dyed in a multitude of bright colors that swirled out from the center like a flame but in splotches, perhaps it was painted? “I’m not your father,” he stated as softly as he could muster with the building panic in his chest.

The child looked wounded their bright orange eye lights squinted as they scrutinized the larger flame. “Yes you are,” they stated with a defiant stamp of their foot.

“No, my name is Grillby. I’m with the Royal Guard, I can help you find your Dad,” he assured in his most professional tone.

The child looked positively cross, “my Dad  _ is _ Grillby but he’s a bartender not a Royal Guard.”

Grillby puckered, what’s a bartender? He exhaled a stream of hot air as he forced himself to patience, “do you live in Hotland?”

“No, I live in Camp.” Grillby looked helplessly over to WingDings, he was the only fire monster in the guard, had been that way for a long time. Why was this child in Camp? They had enough settlements surely someone would take him in.

“Okay what about your mom, where does she live?”

“I don’t have a mom.”

He dimmed, “I’m sorry to hear that.”

“No silly, I have a Papster! He lives in Camp with my Daddy.”

Again he shot a look to WingDings for any sort of assistance but the skeleton seemed far too distracted in his attempts to figure out how he had magically conjured a small child. Grillby’s shoulders dropped as he toiled around with what to do, he supposed they should start at Camp. “I’m going to take you to Camp is that okay?”

The child nodded then quickly latched onto his hand. Grillby’s flames sputtered in sparks surprised at how tickled he was by the complete trust. Upon standing the child barely came above the top of his knee, though the top of his red flame was a bit higher than that. “Dings I’m taking them to Camp, I’ll be back-”

WingDings rose to his feet a bit shakily, ‘I need to apologize to their parents for whatever caused this.’ He signed his eyes fell to the child just barely managing to hide his repulemsent. Dings never had a lot of luck with children, the ones that didn’t run terrified from him tended to ask too many questions. 

‘Child what is your name?’ He signed quickly.

They tilted their head to the side as they thought. They pulled their hand out of Grillby’s grip then signed back, ‘I am learning.’

Grillby turned the child’s attention back to him, “what’s your name?”

“You don’t remember?” They cupped their hands over their soul as black began to form under their spark like eyes.

Tears? Fire Eternal’s couldn’t cry liquids, what was this child? “That’s what he asked, do you want to tell him?”

“Oh!” The child shyly hid his face behind Grillby’s hand, “I’m Lumi Berlin Gaster,” they stated proudly while mumbling around Grillby’s hand.

‘G-A-S-T-E-R?’ WingDings eyed Grillby, ‘my I didn’t know you were married to someone with a last name. Is that a title or are they from a noble family?’ He teased a sneering grin tugged tight across his face.

“I’m not married,” Grillby scoffed. The child’s flames spat sparks as he stared defiantly up to the older flame but they seemed to drop it in place of watching their footing over a series of large rocks scattered about the cavern floor. Grillby would gently lift the child by the arm over particularly large ones to which Lumi would giggle while cycling his legs in the air.

“Higher!” They called as they jumped over a broken column.

Grillby entertained the child as he swung his arm up quickly to lift Lumi onto a ledge that ran along their path. This child had hardly a care in the world and their enthusiasm- was a bit infectious. He found himself glowing brighter with a smile cut across his face as he escorted the tiny flame.

“Daddy are you sick?” Lumi jumped from the ledge and into Grillby’s arms. 

Grillby held the child close to his chest as they rocked back to see his face, “I’m not your father,” he reiterated, “and no I’m not sick.”

Lumi ran their hand against the flames on his face their bright red tainting his own flames like a sunset, “they don’t move right.” Grillby crackled without much thought as he looked back to WingDings and that dang smile across his face. He wanted to bite out an insult but probably best not to do that in front of the child.

“Where are the stars?” Lumi asked with their head tilted back to observe the ceiling.

“In the sky, we’re Underground.”

“Why?”

“Because the human’s trapped us down here.”

“That’s not very nice,” they shook their head, “they wouldn’t do that!”

WingDings scoffed out a comment in his own Font but Grillby just barely caught the word ‘thought’ at the end of his hand signs. At his voice the child perked up and looked around in an attempt to identify the origin. WingDings shut his teeth tight then attempted to burn a hole in the cavern floor with his eyelights.

“Hey Daddy?”

“Hm?” Why did he answer to that?

“Who is that?” They pointed back to their skeleton shadow.

“That’s a friend of mine, his name is WingDings,” he stated simply.

The child cupped their hands over their face to repress their giggles, “that’s a silly name.”

Grillby shrugged and with a teasing smile back to WingDings stated: “it is.”

WingDings grumbled as he followed them his arms crossed as he worked over what on earth the mechanism had to have done to displace this child. It was difficult to concentrate with the hundreds of questions the tiny child spat perusing through his mind like lightning bolts. As fun as it was to tease Grillby about the child’s insistence on calling him Dad seeing the Fire’s soft care for the child was- endearing? That wasn’t right. Enjoyable? Humorous. It was going to bother him if he couldn’t find the right word.

Regardless the child didn’t seem to notice anything amiss, entirely convinced Grillby was their father. Which didn’t make any sense. There weren’t any other monsters quite like Grillby in the underground let alone one that shared a name. But the child- Lumi, spoke earnestly and children weren’t so trusting of those outside of their family. Judging by the kid’s speech pattern they had to be around four, he supposed going off of what he’d learned from Toriel when Grillby was just a spark.

Another question. He sighed as the soldier answered it patiently. The child had a distinct Font which was a trait he’d only ever known skeleton’s to have. The letters were thick and dark, rounded, a bit on the tall side, and they didn’t seem to be distinctly upper or lower case. Everything about this was a puzzle that wouldn’t be solved until he figured out exactly what the machine did.

When they arrived at Camp it was as empty as it always was around this time. All of the guards that inhabited the tents that were littered about were out on duty. They wouldn’t be able to find anyone like this let alone Grillby’s doppelganger. 

“Dings,” Grillby snapped and WingDings focused back on the monster. “I’m going to go find some guards will you watch Lumi?”

‘Absolutely not,’ his fingers clicked, ‘I am terrible with children.’

“Lumi’s a good kid,” he ruffed up the flames on the top of their head but looked a bit confused by the texture they met, “you’ll be fine.”

‘Grillby I can’t even talk to it,’ he reminded his friend with as patient of an expression as he could muster.

“I’ll be right back,” he assured him as he wandered away from them.

‘Grillby,’ he signed harshly but it was pointless with the monster turned away from him.

Lumi trotted after Grillby but WingDings put his hand on the child’s shoulder surprised it wasn’t as round as Grillby’s. In fact it felt nearly skeletal. He tilted his head in observation before the child ripped their shoulder away, “I wanna go with Daddy!”

WingDings shook his head. 

Lumi took off running until they were met with a fence of bones in front of them. The child looked indignantly back to WingDings before they ran to the edge of the fence only to be greeted with more bones. They dashed to the otherside just to find themselves trapped in a pattern. He wasn’t sure why Grillby didn’t want the child to follow him he just knew that’s what was asked of him.

The child huffed, bright purple sparks rained to the ground as they stomped. Their meager form shuttered as they glared their orange eyes at him. 

Perhaps the child had a brave soul? The color seemed to compliment them, and their defiance certainly fit. “I wanna go with Daddy,” they pouted.

WingDings found it very difficult to believe that any self respecting adult would desire to be called Daddy let alone Grillby. Just the idea of Grillby being a father- being married? just seemed preposterous. Obviously he was not this child’s parent no matter how much they insisted otherwise but it still stuck in his head because- Grillby would do really well in a domestic setting. Cooking, cleaning, working a simple trade of some sort that kept his hands and mind busy. The thought was pleasant but unlikely. His friend needed a purpose and he’d anchored it to his sword.

Sniffling pervaded the air as the child took sharp intakes of air. They were scrunched around their knees again, hands cupped over their face like when they’d first met. WingDings scratched the back of his head, what was he really supposed to do? When he approached the child they scurried behind a boulder to better hide themselves.

This child hated him.

“Daddy,” they wailed, “Papster!” Soft hiccup like sobs escaped them as they cried black tears into the dirt.

WingDings opened his mouth to speak but clamped it shut. He tilted his head back in a long groan before he sat to the right of the child against the stone. His gloved hands drummed against the ground in tight restricted movements that pinched in the joints. 

The child’s glow dimmed lower and lower until he disappeared into the shadows. WingDings turned his head around the corner to see the child nearly drowned out by the hood on their shirt.  _ That’s not good for little flames _ , WingDings chortled before he pulled the hood back.

The bright red and purple flames were barely more than embers that fluttered lazily about their core. It wasn’t quite a core though, not like Grillby’s craggy molten rock of one anyways. These shapes were precise and thin, Lumi turned exposing large black eye sockets their orange eye lights shrunk down in their panicked state. The child was a skeleton, though not quite, their bones were marbled in black and white but it didn’t seem to be from the fires the child was previously engulfed in.

Lumi covered their skull with their hood their jagged fused jaw smile just barely visible in the dim lighting of the Underground. “Look what you made me do,” they scratched black tears from their sockets, “I hate this. I hate being like this. And I’m cold.” They rubbed their humeruses as they spat out the words like drops of hail.

WingDings reached out to the child guilt that he had not only thrown this child out of what comfort they lived in but now inspired them to extinguish themselves settled against his vertebrae like a sin. What was he supposed to do? He held up a finger to the child then removed his gloves, ‘I hate these.’ He traced the edge of the circle in his palm in case the child didn’t recognize the signs.

Lumi considered WingDings’s hands for a long while before he delicately laced his marbled thin fingers between his pristine white ones, “they’re like Papster’s,” they stated slowly. Their tiny fingers squeezed gently before their sockets scrunched in concern, “but you’re so small.”

“Lumi?” Grillby called. The child unlaced their fingers immediately and dashed directly into Grillby’s outstretched arms. 

WingDings fidgeted with the glove in his hand a bit uncertain as how to respond to the delicate sensation between his fingers that lingered even after contact was dropped. He always tore away, always bit back any sort of entrapment especially near his hands- except with Grillby, yet the thought never even occurred to him. His natural reflex was somehow repressed. His fingers cupped over his soul as the sensation tucked into his memory.

“Was WingDings mean to you while I was gone?” Grillby mused his natural yellows grew brighter.

“Yes very much so,” the child smothered themselves against Grillby’s tunic. “He ex-ting-uished-ed me!”

“Extinguished?” He pulled the hood off the child’s head and did his best to hide the greens that laced through his flames. Lumi pulled the hood back over their skull then tucked themselves back into Grillby’s shoulder. The rattling of bones filled the air with a distinctly skeletal rattled.

‘Lumi’s a skeleton?’ Grillby signed to WingDings.

WingDings shrugged his shoulders, ‘I have no idea I’ve never met one that prefers to be on fire.’

Grillby leveled a glare, ‘I know one that sure tries sometimes.’ WingDings rolled his eyelights.

“Daddy I’m cold,” Lumi complained. The flame wrapped his arms securely around the child hoping his natural warmth would be enough. 

He bounced them in his arms for a while and the motion seemed to lull them into a comfortable sleep. Grillby removed the hood from the child’s head taking in the marbling across the bones and the malformed fanged smile. ‘Repulsive isn’t it?’ WingDings signed.

“Don’t you dare say that about a child,” he hissed.

WingDings took a step back, ‘but what  _ is it _ ?’

They both appeared to be at a loss on that one. ‘What did you find out?’

“No kids live here,” he replied flatly, “I don’t know what to do.”

‘Me neither, seems to like you well enough.’

“Because they think I’m their dad,” he looked down to the slumbering peacefulness of the figure in his arms and his own expression lightened.

‘You’re good with them,’ WingDings signed with a lopsided smile.

“Yeah.”

Silence drifted between them as they watched flames begin to build off of the skeleton frame until they ignited back into the regal purple and bright red from before. Their shaking stilled but still they clung to Grillby’s collar, their face buried in his collar. ‘Wish I could draw. This won’t ever happen again.’

His face softened as if he hadn’t considered the fact, “I’d never thought about this before.”

‘About what?’

“Holding a child, having them look to you with need and acceptance,” he traced his finger along the line where the red and purple flames met. “I kinda wish it was possible. Settling down, making a home,” he chuckled, “doesn’t sound too terrible.” 

‘Well look who does in fact have an imagination,’ WingDings mused.

“Imagine me settling down with a monster who has a last name,” he faked a swoon with Lumi still secure in his arms as his glow dimmed. He looked over to WingDings as that sinking twisting feeling from earlier situated itself back into his stomach. 

All sound cut out from around them as if completely as if it had never existed at all. The pair stepped closer together as the room grew darker. A large gray door that had never been there before yet neither of them could recall what the stonework behind it looked like sat against the hallway. WingDings had bullets at the ready as the door slowly creaked open.

A sound similar to one of WingDings’s failed experiments replaced the emptiness of sound. To Grillby it was unintelligible but WingDings knew exactly what the symbols in his skull were: “Lumi it’s time to come back home now.”

Lumi stirred from their sleep at the sound then curled deeper into Grillby’s arms. Grillby crackled at the contact before he stepped warily towards the door with WingDings right beside him. The entryway was nothing but pitch darkness. Still the impression of a figure formed in their minds. A tall thin monster with cracks along his skull dressed all in black with holes in the palms had their hand extended towards the child.

Grillby clutched the child protectively to him his flames flared out as they grew wild in defense of the small monster in his arms. Lumi tilted their head away from Grillby just enough to catch site of the door, “Papster!” They sat up and leaned toward the doorway.

“Come on Little Lumi it’s time to go,” the voice called through a series of unintelligible sounds.

“What about Daddy?”

“Daddy is waiting for you at home he’s quite worried,” the monster’s voice was oddly warm even through the harshness of the Font it almost sounded content. WingDings tapped his teeth as he tried to place how that sound could even occur.

Lumi slipped from Grillby’s arm. WingDings couldn’t help but snicker at the the pathetic snap of flames his friend’s flames emitted as the child fell from his grap. Confusion sparked across Lumi’s flames as they stared between Grillby and Papster before they quickly hugged the flames legs. “Bye bye Grillby.”

Grillby rubbed the flames on the top of his head, “good bye Lumi.”

They ran over to the door but as they clutched the doorknob they turned back with a stern expression, “and you be nice WingDings!” With that the door was tugged shut and the cavern was returned to the emptiness of before.

The pair stared at the door for a long while with complete understanding that something entirely out of the ordinary had just occurred. ‘That was my Font.’

‘Do you think- was that us? Is Lumi our kid?’

‘It has to be an alternate timeline,’ WingDings rationalized.

“Why can’t it be this one?” Grillby was surprised at the hurt tone in his voice.

‘Well if we want to start at the base Eternal’s such as yourself can’t really procreate.’

Grillby’s flames grew magenta, ‘and you don’t know how skeletons can.’

His face burned to a violent violet, ‘well yes there’s- uh, that too.’ He rubbed the magic out of his face until it was cool to the touch again, ‘and to put it simply we don’t have those feelings for each other.’

The temperature in his core dropped. Right. Of course they didn’t. He scratched at his forearm desperate for a change in subject. “Where’d the door go?”

‘What door?’ WingDings followed his friend’s line of sight to the cavern walls.

“The-” He furrowed his brows, what was he talking about?

A chirping of automated noises escaped WingDings as a pathetic groan, ‘I can’t believe that machine broke it took me forever to get those parts,’ WingDings’s hands bemoaned.

Right, the machine. Grillby chuckled, “you’ll build it better next time.” His eyes lingered on the cavern wall convinced something had just occurred there but unable to place what it had been. Oh well, someone had to keep this skeleton out of trouble.

**Notes for the Chapter:**

> Papster is Papa+Gaster something I imagine Sans would convince the child into calling him.
> 
> I tired writing the “oh no Gaster made babies in his lab” cliche that I love with the Gaster I usually write and- it got sad. But I liked the idea of Gaster and Grillby play with a small child for a little bit so I messed around until I found something I liked.
> 
> Hope you enjoyed!


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